On the nature of the two-positron bond: Evidence for a novel bond type

The nature of the newly proposed two-positron bond in (PsH)2, which is composed of two protons, four electrons and two positrons, is considered in this contribution. The study is done at the multi-component-Hartree-Fock (MC-HF) and the Diffusion Monte Carlo (DMC) levels of theory by comparing ab initio data, analyzing the spatial structure of the DMC wavefunction, and applying the multi-component quantum theory of atoms in molecules and the two-component interacting quantum atoms energy partitioning schemes to the MC-HF wavefunction. The analysis demonstrates that (PsH)2 to a good approximation may be conceived of two slightly perturbed PsH atoms, bonded through a two-positron bond. In contrast to the usual two-electron bonds, the positron exchange phenomenon is marginal in the considered two-positron bond. The main stabilizing mechanism of bonding is a novel type of classical electrostatic interaction between the positrons, which are mainly localized between nuclei, and the surrounding electrons. To emphasize its uniqueness, this mechanism of bonding is proposed to be called gluonic which has also been previously identified as the main deriving mechanism behind formation of the one-positron bond in [H-, e+, H-] . We conclude that the studied two-positron bond should not be classified as a covalent bond and it must be seen as a brand-new type of bond, foreign to the electronic bonding modes discovered so far in the purely electronic systems.Comment: main text plus supporting informatio

Effects of silver nanoparticles (Ag-NPs) on testis histology and hormones of pituitary-testicular axis in small laboratory mice (Mus musculus)

Background and aims: Regarding Ag-NPs are able to pass through biological memebranes. So, this study aimed to investigate effects of silver nanoparticles (Ag-NPs) on testis histology and hormones of pituitary-testicular axis in small laboratory mice (Mus musculus). Methods: In this experimental study, a group of 36 BALB/c adult male mice (average weights; 28.5±3 g) were randomly divided into three groups; one control and two treatment groups (n=12 each). The treated groups 1 and 2 received 20 and 50 ppm concentrations of Ag-NPs, respectively. Sampling was done on days 7, 21 and 40 of the experiment. Four groups of mice in each group were anesthetized by anesthetic substance (10 m/L ketamine, 0.5 m/L acepromazine, 2 m/L diazepam and xylazine less than 0.5 m/L) in amounts less than 0.01 m/L by insulin syringe with muscle injections. Blood sampling was obtained directly from the ventricle and serum samples were rotated for 10 min at 3000 rpm. A didgital babalne was used to weigh changes of body weight and biomass of the testes. Histological slides were preapared form the testes and then satined by H and E stining method. The data were analyzed by one-way Anova using SPSS. Results: The average of mice body weight did not show any significant difference. Howvere, remarkable histological changes were found in the 50-ppm Ag-NPs treated group than to 20 ppm treated group. Serum level of LH increased 8% and 31% in the treated groups one and two, respectively. Howver, serum level of FSH did not show any significant differnec between both tratement groups and the control. Conclusion: The use of Ag-NPs can lead to hormonal and histological changes in the male testis and consequently affects the male reproductive system and fertility

Information and communication technology and entrepreneurship development

Information and communication technology is advancing rapidly and has led to the fundamental changes in the world community. Activities, jobs, skills, cultures, needs etc. have been impressed and transformed by this technology. Undoubtedly, entrepreneurship has a major role in the development of these technologies; however, these technologies also influence the entrepreneurship and in other words, have created a modern entrepreneurship. In this regard, information and communications are two basic required tools for every entrepreneurial activity. Today, information technology has spread widely in the community and has integrated into all aspects of life. Entrepreneurship is the process of creating something new by spending a lot of time and effort and accepting financial, emotional and social risks to gain financial resources, job satisfaction and autonomy. In fact, information technology is considered as the driving force by which, in addition to mobilizing the job and employment wheels, leads to the economic growth and dynamics of community and the creation of a new kind of economy, that is called knowledge-based economy. This article has tried to analyze the concepts of information and communication technology and entrepreneurship and also has considered the interaction of information technology and entrepreneurship